1. Field of the Invention
This invention relates to recessed fixtures, and particularly to an improved fixture frame allowing the frame and fixture housing to be mounted flush with ceiling support members.
2. Description of Prior Art
As an energy conservation measure, many buildings are being constructed with a continuous vapor/air-flow barrier between conditioned (heated or cooled) spaces and unconditioned spaces (attics, wall cavities, etc.). The intent of the barrier is to retain conditioned air within the building's outer envelope thereby reducing heating/cooling energy costs and to reduce the seepage of moisture into unconditioned spaces where condensation would damage materials. To meet this demand, it is becoming increasingly popular for recessed fixtures, such as recessed lighting fixtures, to be constructed with sealed housings to reduce airflow through the fixture. The Model Energy Code, Washington State Energy Code and many local ordinances require lighting fixtures with sealed housings that comply with prescribed leakage testing conducted in accordance with ASTM E283 "Standard Test Method for Rate of Air Leakage Through Exterior Windows, Curtain, Walls, and Doors" standards. Additionally, many utilities offer rebate programs that promote sealed fixtures.
Further complicating sealed fixture design are requirements that fixture wiring be accessible at a junction box at each fixture for installation and maintenance purposes. Additionally, sealed fixtures rated for both ceiling and no-ceiling access must allow for a sealable opening in the housing to access the junction box from either the room side or the attic side of the fixture.
Commercially available sealed lighting fixtures are typically provided with gaskets, tapes and/or chemical sealant applied at the seams and holes in their housings. These sealing methods involve costly materials, complicate fixture assembly and may degrade over time and may not properly reseal.
To properly dissipate heat generated by a lamp (bulb), sealed recessed light fixtures require housings having sufficient volume. It is an industry standard to provide mounting bars to mechanically attach recessed fixtures to building structural members. These bars have length exceeding the width of the fixture mounting frame because the mounting frame is usually rectangular. Buildings have structural members spaced at distances prescribed by code. These factors sometimes conflict with each other and a fixture having maximal volume for heat dissipation has a mounting frame size which will not allow mounting bars to fit between building members.